The present invention is directed toward a method of forming a heat-resistant chocolate or chocolate-like composition and more particularly, toward modified products that demonstrate reduced apparent viscosity in the molten phase. As a result of this reduced apparent viscosity, these products may be handled in the same manner as unmodified compositions. Such products have a reduced tendency to melt or to deform at elevated temperatures and have a tendency to stick to fingers or packing materials.
Chocolate products are typically mixtures of liquid cocoa, cocoa butter, sugar, lecithin, and possibly milk and flavoring substances. Chocolate-like products contain substantially the same ingredients as a chocolate composition and also use any number of vegetable fats, cocoa butter replacers and/or extenders. Since the resulting fat content of these products is relatively high, the corresponding melting point is a function of the melting point of the fat contained therein.
Ordinary chocolate and chocolate-like products characteristically tend to melt at temperatures as low as 30° C. As a result, chocolate candies, chocolate, and chocolate-like coatings for biscuits, cookies, and confections quickly lose their original appearance, and are no longer suitable for consumption when they have been exposed to high temperatures.
Many processes have been proposed to avoid some of the disadvantages normally associated with ordinary chocolate products. The products obtained by these various methods, which may have more heat-resistance than their ordinary counterparts, often have an unpleasant taste or texture (“mouth feel”), are expensive to produce commercially, require the production of separate ingredients, cannot be produced within established manufacturing processes, or are beyond the current legal definition for chocolate.
U.S. Pat. No. 2,166,806 discloses a product and method for preventing the separation of oils, specifically in peanut products, so that such peanut products, for example, peanut butter, will have a reduced tendency to segregate. This patent describes the addition of glycerine, a polyol, to the peanut product, in an amount upward of one-tenth of one percent, and as high as twenty percent. However, the products and processes disclosed in this patent apply only to peanut products. The potential uses with chocolate and chocolate-like compositions are not addressed. It must be noted that the fat in peanuts is substantially liquid at ordinary temperature (20° C.) and, therefore, has no bearing on or any reference to melting. A disadvantage to this process is that the peanut product to be modified thickens rapidly and allows little time for further use of the product. Also, additional equipment is needed to incorporate the glycerine at the latest possible time before further processing to prevent premature setting. Furthermore, the elevation of viscosity and yield value of the modified peanut product and its impact on the product's commercial production are not addressed.
European Patent No. 459,777 discloses a structured fat emulsion for incorporation into a confectionery coating as the fat ingredient. A disadvantage involved with this process for producing a confectionery coating containing a structured fat emulsion is that the emulsions described are inherently unstable and are therefore difficult and expensive to produce and store. Furthermore, the machinery required to produce the emulsion is alien to chocolate manufacture, thus significant additional capital investment would be required. Another disadvantage is that the preferred fat is partially hydrogenated fat. Such fats are thought to engender physiological properties that are currently thought to be undesirable, and are, therefore, less commercially desirable. Additionally, the use of such fats is not allowed as they are beyond the current legal definition for chocolate.
U.S. Pat. Nos. 5,149,560; 4,446,166; 4,081,559; 4,045,583; and 2,904,438 and Swiss Patent Nos. 410,607 and 409,603 demonstrate the use of water or moisture in chocolate compositions. Products produced by the methods described in these patents are prone to suffer an effect known as “sugar bloom”and initiate a progressively increased coarse mouth feel as the water evaporates and the sugar crystallizes. Other disadvantages may include: a lack of heat-resistance below the immediate surface of the chocolate, the need for expensive thermal treatments, controlled humidity and difficult and costly storage conditions, and deficient quality of the finished products.
Swiss Patent Nos. 399,891 and 489,211 describe methods of incorporating amorphous sugars into a chocolate composition during manufacture. The sugars form a lattice structure that prevents collapse of the mass when the temperature exceeds the melting point of the chocolate fat. Such a structure is delicate, unstable, and difficult to incorporate in a commercial setting.
U.S. Pat. No.4,446,166 describes a chocolate composition containing a water-in-fat emulsion which provides a product containing at least 20% of the fat in solid form. The water-in-fat mixture, however, does not remain in liquid form during processing. Also, the presence of such solid materials may result in an undesired rough texture or mouth feel.
Other methods of moisture inclusion or fat immobilization have been attempted. A disadvantage described in subsequent literature has been the elevation of chocolate viscosity and yield value that occurs as a result of the employment of these methods.
It is known that Newtonian liquids (e.g., water) flow as soon as force is applied. Viscosity remains constant regardless of the rate of shear. Viscosity refers to the measure of the internal friction of a fluid that provides resistance to shear (motion) when a fluid is stirred or poured. The greater the forces of internal friction (i.e. the greater the viscosity), the less easily the fluid will flow.
Non-Newtonian liquids are liquids whose viscosities vary according to the rate at which they are stirred (also known as “shear rate”). They include plastic, dilatant, and pseudoplastic liquids, characterized by the way a fluid's viscosity changes in response to variations in shear rate.                1. Plastic. This type of fluid will behave as a solid under static conditions. Prior to the inducement of any flow, a minimum force is required to start the liquid moving.        2. Dilatant. The viscosity increases with an increasing shear rate.        3. Pseudoplastic. The viscosity decreases with an increasing shear rate.        
Yield value is the minimum force required to start a non-Newtonian liquid moving. When the yield value upon a non-Newtonian liquid is achieved and exceeded, fluidity results. The higher the yield value, the more resistant the material is to flow. “Plastic Viscosity” is a measurement relating to the amount of energy required to keep certain non-Newtonian liquids moving once they have started to move.
Molten chocolate is a non-Newtonian fluid, but is typically referred to as a pseudoplastic fluid, demonstrating unique rheological characteristics. Viscosity measurements of chocolate in the molten state may be referred to as “apparent viscosity”, as variations of shear rate will affect the measured viscosity. Typically, apparent viscosity is a function of applied shear rate and shear stress without regard to yield value. See, Nelson and Beckett, Industrial Chocolate Manufacture and Use, 1988; Instruments and Control Systems. vol. 32, No. 6, Jun. 1959; and “More Solutions to Sticky Problems”, Brookfiled Engineering Laboratories, Inc., 1985.
U.S. Pat. No. 4,464,927 discloses a method for increasing the viscosity of a chocolate composition so that the composition will be non-flowable at temperatures well above the normal melting point of the cocoa butter (or in the case of imitation chocolates, the melting point of vegetable fats and the like). This patent describes adding a liquid polyol, for example, glycerine, sorbitol, or mannitol of 0.2 to 5.0 wt % to a chocolate composition after tempering. A perceived disadvantage of this process is that the chocolate product to be modified sets rapidly, i.e., between 15 to 60 seconds, and allows little time for further processing of the chocolate, for example, molding or enrobing. Another disadvantage of this method is that special additional equipment may be needed to incorporate the polyol at the latest possible time before further processing of the chocolate to prevent premature setting of the chocolate.
U.S. Pat. No. 5,523,110 discloses a heat-resistant chocolate which comprises mixing of a polyol gel in particulate form with a flowable chocolate or a flowable mixture of ingredients for preparing chocolate and chocolate-like compositions. The polyol gel is formed by the use of gelling agents such as pectin, xanthan gum, locust bean gum, kappa-carrageenan agar, sodium alginate, gelatin, and iota-carrageenan. Other gelling agents, such as polysaccharides, for example, glucomannan, are suggested for use to form a firm gel around a polyol. A disadvantage of this method is that such gelling agents are not permitted in chocolate by regulation in many countries, and therefore such compositions may not labeled as “chocolate.”
U.S. Pat. No. 5,523,110 also provides a gelation method by which a dry polyol mixture containing up to 95% by weight of water is used. A disadvantage of this method and process is that the product produced may have an undesirable taste and/or texture (“mouth feel”) due to the presence of a high amount of water in the chocolate. In addition, the patent further provides a method for forming and dispersing a particulate polyol gel by “ . . . freezing the polyol gel from about −170 C. to −200 C. and then grinding it in a cold grinder . . . .” A disadvantage of this method and process is the cost prohibitive use of refrigerants such as liquid nitrogen needed to achieve low temperatures. Such a technique is alien to commercial chocolate production.
U.S. Pat. No. 5,445,843 discloses a process for improving the heat resistance of chocolate or chocolate-type products with a reduced tendency to deform at elevated temperatures including the step of mixing a polyol encapsulated within an edible lipid, for example, fat or oil, and added in particulate form to a flowable chocolate composition. The resultant chocolate product is described as having a slower “setting time” when compared to other methods. A disadvantage of this process is that in a commercial setting, it may be difficult to maintain the required “gentle mixing” of the composition. That is, pumps, mixers, and other operations in a commercial chocolate production setting may apply more mechanical energy than allowed by this patent.
Furthermore, commercial chocolate is best stored at about 400° C. See, R. B. Nelson and S. Beckett, Industrial Chocolate Manufacture and Use(1988). In addition, commercial chocolate is typically melted to 60° C.; lowered to between 46 and 49° C.; and pumped at a temperature between 43.5 and 49° C. prior to tempering. See, D. Hawk, et al., National Confectioner's Association—All Candy Expo educational session “Chocolate Handling, Problems and Solutions,” (Jun. 12, 1997). Handling of modified chocolate beyond the parameters set by U.S. Pat. No. 5,445,843 may cause premature setting of the modified chocolate and, in a commercial setting, may result in disastrous consequences. Other disadvantages of this process are that the encapsulated particulate must be produced as a separate ingredient, and the particulate must be stored so as to remain in a solid form during the mixing and processing of the chocolate composition to prevent a premature setting.
U.S. Pat. No. 5,445,843 provides the following example:                “5 parts of the encapsulated glycerol as prepared . . . are mixed with 100 parts of a flowable mixture of conched chocolate at 30 degrees C. for 15 minutes. The chocolate remains flowable for several minutes without setting . . . ”        
It is well known to those skilled in the art that molten chocolate in a commercial setting must remain flowable for many hours.
It has been described and demonstrated in the prior art discussed above that the increase in viscosity of a chocolate composition by polyol or water inclusion would render certain methods impractical or unusable in a commercial setting. The prior art teaches that chocolate and imitation chocolate compositions which exhibit high viscosity in their fluid phases are to be avoided. It is also self-evident to those skilled in the art that a method to produce heat-resistant chocolate compositions considered typical to chocolate manufacturing would be preferred over the use of special processing equipment. Furthermore, special handling of ingredients and/or finished products, for example, high humidity or low temperature storage is not a preferred approach.